Muscle physiolgy - Muscle Physiology Objectives To...

1 Muscle Physiology Objectives: • To understand the organization of a skeletal muscle fiber and sarcomere and the molecular basis of muscle contraction • To understand excitation-contraction coupling • To learn organization and function of different muscle types

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3 Skeletal Muscle • Often described as voluntary muscles • Contract in response to a signal from a somatic motor neuron – cannot contract on their own, contraction not influenced by hormones • Bulk of muscle in body and 40% of body weight • Attached to bones by tendons (collagen) • Origin of a muscle is the end attached closest to the trunk • Insertion of the muscle is the more distal (distant) attachment

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6 Muscle Fibers • Skeletal muscle is a collection of muscle fibers • Each muscle fiber is made up of several hundred nuclei on the surface of the fiber • Muscle fibers are the largest cells in the body - many fused cells • Groups of muscle cells that function together and share a common motor neuron are called a motor unit – small muscles have a few motor units – large muscles may have several thousand motor units • Fine touch – 1:1 nerve to fiber – Finger tips • Big muscles – 1: 2000 nerve to fiber – Leg muscles